Resistive sensor based on conductivity change of conductive polymer and measuring method thereof

Abstract

A resistive sensor for an analyte comprises a substrate, a conductive polymer layer and an oxidase layer. Hydrogen peroxide is produced via the reaction between analyte and oxidase when a liquid sample is applied to the sensor of the present invention. The produced hydrogen peroxide can oxidize peroxidase, which can be reduced by oxidizing the conductive polymer, thus resulting in decreased conductivity of the conductive polymer for determining the analyte concentration in the liquid sample. The present invention may be used for developing miniaturized and disposable electronic microsensors with high sensitivity and fast response, which can detect analyte level in typical physiological environment for routine monitoring.

What is claimed is: 
     
       1. A resistive sensor for an analyte, comprising:
 a substrate; 
 a conductive polymer layer configured on the substrate and made of polyaniline or derivatives thereof, wherein a peroxidase is configured on the conductive polymer layer and used for oxidizing the conductive polymer layer so that a conductivity of the conductive polymer layer is decreased after applying an analyte, wherein a conductivity change of the conductive polymer layer is related to a concentration of the analyte; and 
 an oxidase layer configured on the conductive polymer layer and provided with an oxidase configured thereon, wherein the oxidase is separated from the peroxidase and used for oxidizing the analyte to generate a hydrogen peroxide so that the peroxidase is oxidized by the hydrogen peroxide. 
 
     
     
       2. The resistive sensor for an analyte according to  claim 1 , further comprising:
 a first electrode and a second electrode, wherein the first electrode and the second electrode are electrically connected with the conductive polymer layer. 
 
     
     
       3. The resistive sensor for an analyte according to  claim 2 , wherein the first electrode and the second electrode are configured underneath a partial area of the conductive polymer layer. 
     
     
       4. The resistive sensor for an analyte according to  claim 1 , wherein the conductive polymer layer is pretreated with acid. 
     
     
       5. The resistive sensor for an analyte according to  claim 1 , wherein an initial current of the conductive polymer layer before applying the analyte ranges from 10 to 1000 μA at bias of 100 mV. 
     
     
       6. The resistive sensor for an analyte according to  claim 1 , wherein the surface of the conductive polymer layer is modified with propane sultone. 
     
     
       7. The resistive sensor for an analyte according to  claim 1 , wherein the oxidase layer further comprises a dialysis membrane and the oxidase is configured within the dialysis membrane. 
     
     
       8. The resistive sensor for an analyte according to  claim 1 , wherein the peroxidase comprises horseradish peroxidase, lactoperoxidase or microperoxidase. 
     
     
       9. The resistive sensor for an analyte according to  claim 1 , further comprising:
 a sensing element electrically connected to the conductive polymer layer and configured for measuring the conductivity of the conductive polymer layer. 
 
     
     
       10. The resistive sensor for an analyte according to  claim 1 , wherein the oxidase comprises cholesterol oxidase, glucose oxidase, alcohol oxidase or choline oxidase. 
     
     
       11. The resistive sensor for an analyte according to  claim 1 , wherein the oxidase is cholesterol oxidase. 
     
     
       12. The resistive sensor for an analyte according to  claim 1 , wherein the conductivity change of the conductive polymer layer after applying the analyte compared to before applying the analyte ranges from 10% to 60%. 
     
     
       13. The resistive sensor for an the analyte according to  claim 1 , wherein the conductivity change of the conductive polymer layer after applying the analyte compared to before applying the analyte ranges from 20% to 50%.